"He eats an apple."
Translation:Il mange une pomme.
il est mange = he is eat, so it does not mean anything in French.
he is eating uses the gerund form of "eat" to create a continuous tense, meaning "he is currently in the process of eating".
If French, such a verbal form does not exist.
To precisely translate "he is eating", you have to use a phrase "en train de + infinitive": il est en train de manger.
Otherwise, you can still translate with a simple present (less precise but correct) = il mange.
In grammar, genders are not "female" or "male", but "feminine" and "masculine".
All nouns in French are gendered, based on etymology (Latin for the most part). So you have to learn every new noun with its gender.
Tip: learn "une-pomme" as if it were one word, so that you remember it later when you need it.